The present invention relates to a plasma display apparatus using a plasma display panel.
A display device (to be referred to as a plasma display apparatus hereinbelow) using a plasma display panel is small in depth as a feature of the general flat panel display and additionally has a free viewing angle, which helps implement a large screen. Therefore, the plasma display apparatus is regarded as a most likely candidate for large screen flat panel televisions.
However, unlike a display device using a liquid crystal display panel which is also a flat panel display, the plasma display panel has drawbacks that electric discharge is used to display pictures and hence requires large power consumption and radiated interference is strong because the panel has a large area. JP-A-10-282896 describes a technique to suppress radiated interference occurring in a display device.
Radiated interference is caused by, for example, occurrence of an undesired voltage in association with a current change. In the plasma display apparatus, the current used to display pictures is supplied in the form of pulse signals. The current change is quite frequent, which hence leads to the problem of the undesired voltage. Occurrence of the undesired voltage makes a voltage applied to the panel unstable and resultantly deteriorates picture, quality. This exerts direct influence upon quality of pictures displayed on the panel. Consequently, suppressing the undesired voltage to a maximum extent is effective to improve overall performance of the plasma display panel. To suppress the undesired voltage, it is required to minimize an inductive portion and inductance of the associated circuit of the plasma display panel.
To reduce inductance, it is generally effective to reduce the wiring length and to increase the wiring width. When such a measure is not feasible or when an additional measure is required, an eddy current may possibly be used. JP-A-2002-150943 describes a technique to reduce inductance in a plasma display device.
Although it is required to reduce an inductive portion in almost all sections of the circuit, an advantage is remarkably obtained by reducing the inductive portion in a path of a large current. In a plasma display panel, the largest current flows in a sustaining discharge circuit. Specifically, a sustaining discharge current, i.e., a current to display an image through electric discharge flows through the sustaining discharge circuit. This circuit is used to emit light in the panel. In the overall plasma display panel, currents of pulse signals having a current value exceeding 100 ampere (A) flow through the circuit at same timing.
The sustaining discharge circuit has a length almost equal to a lateral width of the plasma display panel and forms a long loop and hence has high inductance. According to study of distribution of inductance in the circuit, it is known that large inductance appears in a pair of printed circuit boards and ground level wiring connecting the circuit boards to each other, excepting the main section of the panel. It is desired to reduce inductance in these sections for the following reason. Since a large current flows through and a high voltage is applied to the panel, adverse influences occur due to a voltage drop, waveform disturbance, and/or occurrence of electromagnetic interference during the electric discharge.
However, none of the above patent articles has given consideration to a configuration to reduce inductance by reducing the inductive portion of the wiring in the printed circuit boards in which a sustaining discharge circuit is arranged.